Lecture 4

Question 1

What are viral attachment factors?

Answer 1

Cell surface components involved in binding of virions

Question 2

What are cell receptors?

Answer 2

Bind virions and mediate entry (trigger conformational changes, cell signaling or mediate endocytosis)

Question 3

True or false: Different viruses can have the same receptor

Answer 3

True

Question 4

True or false: Viruses in the same family may bind different receptors

Answer 4

True

Question 5

True or false: One virus may bind multiple receptors

Answer 5

True

Question 6

True or false: A virus may use different receptors on different cell types

Answer 6

True

Question 7

How do naked viruses bind their receptors?

Answer 7

By capsid surface or protrusions

Question 8

How do enveloped viruses bind to receptors?

Answer 8

Via transmembrane glycoproteins

Question 9

Review virus entry: membrane fusion

Answer 9

Lecture 4 slide 12-13

Question 10

What can trigger fusion of some enveloped viruses?

Answer 10

Low pH in the endosome

Question 11

How does influenza fuse with the membrane?

Answer 11

Review lecture 4 slides 16-17

Question 12

What are Class I fusion proteins?

Answer 12

Perpendicular to membrane (spikes)
Mostly alpha-helical
Form trimers

Question 13

What are class I fusion proteins?

Answer 13

Parallel to the membrane
Mostly beta-sheets
Form dimers

As endosomes acidify, a conformational change causes the fusion peptide/loop to stick into the cell membrane

Question 14

Describe dengue fusion in endosomes.

Answer 14

Lecture 4 slide 21

Question 15

How are viral particles transported inside the cell?

Answer 15

Through actin and microtubule cytoskeletons

Question 16

How do viruses get into the cell nucleus?

Answer 16

Nuclear pore complex: Nuclear localization signal (NLS), docking at the nuclear pore, nuclear membrane disruption

The viral particles release genome segments and can enter through the nuclear pore, the viral particle can dock at the nuclear pore and inject viral genome or can disrupt nuclear membrane